The present invention relates to an evaluation method of evaluating an article, a deterioration diagnosis system for diagnosing a deterioration degree using the evaluation method, a material identification system for identifying an internal material and a quality control system for controlling quality.
A technology of controlling quality of an article by irradiating light on the article to diagnose the physical properties is widely used. The diagnosis of an article by irradiating light on the article and measuring the reflected light is preferable because the diagnosis is affected by an internal material of the article, and the article need not to be contaminated or damaged.
For example, a semiconductor device is required to have high smoothness of its surface. Japanese Patent Application Laid-Open No.11-330185 discloses an apparatus for manufacturing semiconductor devices in which polarized light is irradiated onto the semiconductor device to evaluate a surface state or a film thickness of a semiconductor layer. Further, Japanese Patent Application Laid-Open No.2000-131243 discloses an optical sensor which detects a surface state of an object to be detected by accurately evaluating and correcting a distance between the object to be detected and the measurement instrument. In these optical diagnoses, asperities on the surface are detected by measuring phase difference between incident light and reflected light to accurately measure the phase of polarized light.
Japanese Patent Application Laid-Open No.11-235097 and Japanese Patent Application Laid-Open No.9-222393 propose a deterioration diagnosis system which diagnoses a deterioration degree by measuring a reflection absorbance difference between or a reflection absorbance ratio of two light beams each having an arbitrary wavelength among light beams irradiated on an object from plural kinds of monochromatic light sources, and by referring the relationship between the absorbance difference or the absorbance ratio and deterioration degree.
In addition, Japanese Patent Application Laid-Open No.10-115601 discloses deterioration diagnosis of an insulator coated film in which elastic wave is measured by irradiating light on the insulator coated film.
There are many kinds of physical properties in an article required to be diagnosed. Therefore, in the evaluation methods described above, there exist some physical properties which are not evaluated.
Since needs of miniaturization and close-packing of semiconductor devices are being increased, a technology capable of diagnosing defects in a material composing a product in addition to smoothness of the surface of the material is required in the field of the semiconductor device manufacturing. The technology evaluating materials is useful because the technology can be used for not only the semiconductor device but also for controlling quality of articles. The present invention has been made under the background described above.
Further, in the deterioration diagnosis system described above, deterioration factors not appearing change in the reflection absorbance or the reflection absorbance ratio cannot be diagnosed by the deterioration diagnosing method described above. In regard to deterioration of an article, there are many deterioration factors depending on an environment where the article is placed. For example, for a cable installed in a facility relating to a nuclear power station, the deterioration factors are heat and radiation dose, and the deterioration may progress faster compared to a cable placed in the other facilities. Since the electric insulating property of the cable is degraded by deterioration, it is necessary to change the cable before the deterioration is progressed. There are many reports since there is a large demand for the deterioration diagnosis of cables. Deterioration diagnoses of cable sheathing insulator materials utilizing ultrasonic wave propagation speed are disclosed in Japanese Patent Application Laid-Open No.11-118773, Japanese Patent Application Laid-Open No.10-19856 and Japanese Patent Application Laid-Open No.7-35732. Deterioration diagnosis of insulation materials by detecting small leakage current is disclosed in Japanese Patent Application Laid-Open No.7-245869. In connection with these diagnosis methods, it is described in the Transaction of the Institute of Electrical Engineers of Japan, vol.120-B, No.11, p1437 (2000) that an index of deterioration state is generally expressed by the correlation with elongation characteristic.
Therefore, it is desirable to execute a highly reliable deterioration diagnosis by studying a factor of material deterioration and selecting a method corresponding to the factor.
Further, as described above, progress of deterioration of an article depends on the surrounding environmental condition. Further, when the deterioration diagnosis of cables is performed, in a case where a large amount of cables are laid like in a power station, it is difficult to measure all the cables having different laying time and different laying environment.